Dye sensitized light sensitive systems incorporating an iodide

ABSTRACT

A DYE SENSITIZED ORGANIC PHOTOSENSITIVE COMPOSITION WITH ITS SENSITIVITY EXTENDED BY THE INCORPORATION OF AN IODIDE.

3,565,628 DYE SENSITIZED LIGHT SENSITIVE SYSTEMS INCORPORATING AN IODIDEThomas Howard Garland, El Monte, and Yoshikazu Yamada, Sierra Madre,Califl, assignors to Bell & Howell Company, Chicago, 11]., a corporationof Illinois No Drawing. Filed July 11, 1967, Ser. No. 652,430

Int. Cl. G03c 1/72 US. C]. 96-90 23 Claims ABSTRACT OF THE DISCLOSURE Adye sensitized organic photosensitive composition with its sensitivityextended by the incorporation of an iodide.

CROSS-REFERENCE TO RELATED APPLICATIONS BACKGROUND OF THE INVENTION (1)Field of the invention The field of art to which the invention pertainsincludes the field of photographic chemistry, particularlylight-sensitive compositions including those involving light-sensitivedyes.

(2) Description of the prior art A variety of organic photosensitivesystems are known in the art. Generally they involve two or more organicmaterials which react under the influence of actinic light to produce acolor. As early as 1921, Murray C. Beebe and his coworkers describednumerous organic photographic systems (e.g., U.S. Pats. Nos. 1,574,357;1,574,358;

1,574,359; 1,575,143; 1,583,519; 1,587,269; 1,587,270; 1,587,271;1,587,272; 1,587,273; 1,587,274; 1,604,674; 1,618,505; 1,655,127;1,658,510; and 1,820,593). Generally, these systems relate to the use ofvarious halogen compounds (e.g., iodoform and others) in combinationwith a second ingredient, in which Beebe and subsequent workers havetheorized that light effects the release of a radical from the halogencompound which carries out a color-forming reaction with the secondcompound. Subsequent workers such as Eugene Wainer (e.g., U.S. Pats.Nos, 3,042,515; 3,042,516; 3,042,517; 3,042,518; 3,042,519; 3,046,125;and 3,056,673) and Robert Sprague (U.S. Pat. No. 3,082,086), as well asa number of other workers since the time of Beebe, have continued thedevelopment of various photographic systems involving a photo-energizedreaction of a combination of a halogen-containing compound and one ormore other compounds. Other recent disclosures include British Pat. No.917,919 and Belgian Pat. No. 596,094.

Wainer has suggested (U.S. Pat. No. 3,042,518) the addition of aninorganic iodine compound, such as inorganic iodide, iodate orperiodate, as a method of increasing the photographic speed of some ofthe foregoing formulations. More recently, it has been discovered thatincorporation of certain organic photochemical combinations asdispersions in a continuous phase in which the combinations aresubstantially insoluble, results in compositions of superior speed. Thisdiscovery is described United States Patent O Patented Feb. 23, 1971 inour noted copending application Ser. No. 481,759. The dispersion of thephotochemical materials in the nonsolubilizing continuous phase providesin and of itself a marked increase in photographic speed and theaddition of iodide, per se, has no significant effect on the speed ofthe photosensitive materials in such context.

Generally, the latter, non-solubilized, dispersions are sensitive toonly a portion of the visible spectrum. Meth ods for extending thesensitivity are described in our copending application Ser. No. 523,705,and involve the addition of a dye (or dye base) sensitizer which, byintimate association with the dispersed chemicals, effectively extendsthe optical sensitivity of the system. Even here, however, it may bedesired to obtain a wavelength response longer than that provided by aparticular sensitizer. The only recourse has been to seek a substitutewhich sensitizes in the longer wavelength regions; but the change toanother sensitizer may require sacrificing efficiency and desirablecharacteristics or properties peculiar to the sensitizer originallyemployed and with which the system as a whole has been optimized. Forexample, with our dispersed formulations, certain sensitizers favor apositive-mode reaction, while others favor a negativemode reaction. Itis, therefore, advantageous to be able to extend the normal spectralresponse range obtained with a particular sensitizer by an additive thatdoes not deleteriously affect other aspects of the photochemicalcomposition.

SUMMARY OF THE INVENTION It has now been found that sensitizedphotosystems as just described can have their sensitivity extended evenfurther by the incorporation of an iodide. Thus our inventioncontemplates a photosensitive composition comprising a dispersion oforganic photochemical material in a continuous phase in whichsubstantial amounts of such material are insoluble, a sensitizer for thematerial and an iodide.

Incorporation of an iodide extends the sensitivity of the compositionand generally improves the overall performance of the sensitizer. Incontrast to prior systems, the iodide has no significant effect upon thespeed of the unsensitized composition. Wainer discloses (Pat. No.3,042,518) that a sensitizer may optionally be present with his iodineadditive. In contrast, iodide has no signifi cant effect on ourdispersions in the absence of a sensitizer. Wainer also teaches theequivalency of iodates to iodides in increasing the speed of hisemulsions. Again in contrast, we have found iodates are not operativewith our dispersions.

In a preferred embodiment of our invention, the dispersion ofphotochemical material is capable of yielding color and non-color areasin response, respectively, to high and low levels of exposure. Aninitial low level exposure deactivates the exposed areas againstsubsequent color formation; a positive-mode process is thereforeobtainable. Incorporating an iodide, as per our invention, isparticularly effective in allowing the occurrence of the non-colorreaction with extending portions of the spectrum. Accordingly, a processis provided which comprises: providing a sensitized dispersion ofimage-yielding material in a continuous phase in which substantialamounts of such material are insoluble, the dispersion being capable ofyielding color and non-color areas in response, respectively, to highand low levels of exposure; incorporating an iodide; imagewise exposingthe dispersion to the low level of exposure to deactivate the imagewiseexposed areas against color formation; and then blanket exposing thecomposition to radiation at the high level of exposure to yield color inareas exclusive of the image-Wise exposed areas.

3 DESCRIPTION OF THE PREFERRED EMBODIMENTS The sensitized combinationsthat are improved by our invention are dispersed in the form of discreteglobules in a continuous phase in which the combination is substantiallyinsoluble. Such dispersions are discussed in detail in our above-notedapplication Ser. No. 481,759. Generally, the solid-film-formingcomponent used to achieve a continuous phase may be any of a number ofgenerally photographically inert materials, which are, in most cases,soluble in water or so finely dispersible therein in the concentrationsof use that for practical purposes there is no distinction betvveensolution and dispersion for these materials in the continuous phase.Such materials include the starch and starch derivatives, proteins(i.e., casein, zein, gelatin, thiolated gelatin, etc.), alginates, gums,and the like materials which are generally considered to be naturalderivatives of natural film-forming materials, any one of which in itsconventional water-soluble form is used in the practice of the instantinvention. In addition, synthetic water-soluble film-formers may also beused to particular advantage in the practice of the invention and suchmaterials include polyvinyl alcohol, commercially availableWater-soluble polyacrylics or acrylates (i.e., water-soluble polyacrylicacid salts having substantially the molecular weight and watercompatibility of the polyvinyl alcohol), various commercially availableamine or aminealdehyde resins, etc. Also, a number of cellulosederivative film-formers may be used, and these include the variouswater-soluble cellulose ethers, carboxymethylcellulose,hydroxypropylmethylcellulose, etc. Essentially these materials arephoto-insensitive and their principal function is that of forming thedesired film which will retain the dispersed phase in discrete particleform. Of the above materials, gelatin, casein, polyvinyl alcohol, gumarabic, starch, alkali metal carboxymethylcellulose (e.g., sodiumcarboxymethylcellulose) and hydroxyethylcellulose are particularlyuseful in this invention.

The iodide may be incorporated in the formulation during preparationthereof or may be added later by washing a coating of the formulationwith a solution of 1od1de. When incorporated during preparation of thecoating, 1t may be added to both the binder and photosens tive organicphase, or to the binder only, or to the organic phase only. The termiodide is meant to include both 1norganic and organic compounds yieldingthe monovalent 1 ion. The availability of the I ion is the lmportantaspect of the additive rather than the particular metal or organic groupcarrying the iodide. Binary inorganic compounds of iodine of the typeMI, particularly Where M is an alkali metal or ammonium ion, areincluded, such as sodium iodide, potassium iodide and ammonium iodide.Tetrapropylammonium iodide is an example of a suitable organic iodide.

In general, any amount of iodide will improve sensitlzation; a practicalupper limit is about three weight percent of the formulation andgenerally about 0.005 Weight percent wvill noticeably extend thespectral response of the formulation. A preferred range is from about0.1 to about one Weight percent.

As noted, a sensitizer for the photosensitive material must be present;indeed, iodide has no appreciable effect on our formulation in theabsence of a sensitizer. As a sensitizer, one can use any material thatsensitizes the composition to which it is added to radiation in a regionof the spectrum to Which the composition has otherwise low sensitivity.Generally, it is preferred that such materials have the opticalproperties of, or be, optical sensitizing dyes or dye bases. Referencecan be made to our earlier application Ser. No. 523,705 and to a 1957publication of Brooker and Vittum entitled A Century of Progress in theSynthesis of Dyes for Photography in The Journal of PhotographicScience, vol. 5, 1957, pp. 71-88, the disclosure of such publicationbeing incorporated herein by reference. All of these dyes tend to absorbactinic energy and all have exhibited their ability to transmit theabsorbed energy by a physical molecular contact or by engagement toother molecules receptive of actinic energy for purposes ofphoto-response. Illustrative materials are: compounds having acharacteristic rhodamine ring structure and nominal substitution at anamino group, such as the rhodamines (i.e., aminophthaleins); materialshaving simple (unsubstituted) carbon chains interconnecting fusedheterocyclic and benzenoid ring structures, such as pinacyanole andrelated canbocy-anine, cyanine or isocyanine type dyes or dye bases,such as Ethyl Red; light absorbers containing heterocyclic rings fusedwith benzeuoid rings, such as eosin dyes; and light absorbers having atriphenylmethane structure such as Crystal Violet, Victoria Blue andMalachite Green, including leuco forms thereof and compounds havingthiazine, alizarine, acridine and anthraquinonoid groups or structures,such as Methylene Blue and thionin. In general, light absorbers having astyryl substituent, such as the styryl and azastyryl dyes and dye basis,are particularly useful in our invention, comprising a preferred groupof sensitizers. In general, it is preferred to use an optical dye or dyebase. It is particularly preferred to use a dye base, such as the styryldye bases and vinyl homologs thereof. Particularly effective dyesinclude:

2-( 2-aza-p-dimethylaminostyryl) -benzothiazole,

2- (p-dimethylaminostyryl) -3 ,3 -dimethylindole,

2- (p-dimethylaminostyryl) benzothiazole,

2- p-dimethylaminostyryl -quinoline,

2- (2-aza-p-dimethylaminostyryl)-benzimidazole,

2- (Z-aZa-p-dimethylaminostyryl -thiazole,

4- p-dimethylaminostyryl) uinoline,

2- (p-dimethylaminostyryl) -benzimidazole,

2-3 (3 -ethyl-2 3 -benzothiazolylidene) -propenylquinoline and 2-(p-dimethylaminostyryl) -pyridine,

and the dye bases of each of the above. Each of the above dyes and dyetypes can be used in their dye form or in their dye base form andreference to a dye is meant to include dye bases as well.

Although various dyes have been described as sensitizers for ourinvention, the ability of such dyes to form a color is not important tothe invention except insofar as related to an ability to selectivelyabsorb and/ or transfer electromagnetic radiation. Thus, a sensitizingamount of the sensitizer is used rather than a color-forming amount,which amounts may be different. In general, about 0.01 to about mg. ofsensitizer per gram of image-yielding material is satisfactory.

In a preferred embodiment of the invention, the photosensitivecombination comprises at least two starting agents, a color-yieldingagent and a photoinitiator. Suitable photoinitiators include compoundswhich produce free radicals or ions upon exposure to light of a suitablewavelength, such as the haloalkanes, halomethylnaphthalenes,a-haloketones, halogenated acids, sulfonyl chlorides and aroylperoxides. Such of these materials as are discussed by McCloskey andBond in Industrial Engineering Chemistry, vol. 47, p. 2125 et seq.(1955) are of interest here, and such disclosure is incorporated hereinby reference. Other materials include aromatic hydrocarbonphotoinitiators such as found in US. 2,902,421, substituted benzoinsdescribed in US. 2,722,512, metal mercaptides as described in US.2,738,319, benzene thiols as described in US. 2,861,934, ethyleniccompounds as described in US. 2,716,633 and thiuram monosulfides asdescribed in US. 2,861,933, the disclosures of the above patents beingincorporated herein by reference.

In general, it is preferred that the photo-initiator be an organichalogen compound as these have been found to be the most effective. Suchcompounds are described in detail in our earlier filed application Ser.No. 481,759. In general, organic halogen compounds are preferred inwhich there is present at least one active halogen selected from thegroup consisting of chlorine, bromine and iodine, attached to a carbonatom having not more than one hydrogen atom attached thereto. Examplesof such compounds include carbon tetrabromide, tribromochloromethane,dibromodichloromethane, pentabromoethane, hexachloroethane,hexabromoethane, bromotrichloromethane, bromoform, iodoform,l,2,3,4-tetrabromobutane, tribromoacetic acid, 2,2,2-tribromoethanol,tetrachlorotetrahydronaphthalene, 1,1,1 tribromo-2-methyl-2- propanol,carbon tetrachloride, p-dichlorobenzene, 4- bromobiphenyl, 1chloro-4-nitrobenzene, p-bromoacetanilide, 2,4 dichlorophenol, 1,2,3,4tetrachlorobenzene, 1,2,3,5 tetrachlorobenzene, brominated polystyrene,nchlorosuccinimide, n-bromosuccinimide, 2 chloroanthraquinone,tetrabromophenolphthalein, tetrabromoo-cresol, and the like. Otherexamples can be found in our noted earlier application and also incertain patents issued to Eugene Wainer and Robert Sprague such as US.Pats. Nos. 3,042,515, 3,042,516, 3,042,517, 3,042,518, 3,042,- 519,3,046,125, 3,056,673, and 3,082,086, the disclosures of such patentsbeing incorporated herein by reference.

In a particular embodiment of this invention, it is preferred to use asan initiator an organic halogen compound having the formula where X, Xand X" are halogens, each Y is independently selected from the groupconsisting of halogen, hydrogen, hydroxy, methyl and methylol, and n isselected from and 1, such that when n is O, X and X are Br. Thesecompounds are generally more compatible and more effective with opticaldye sensitizers selected from the dye and dye base form, particularlythe styryl dyes and dye bases, and are preferred in such combination.Examples of such compounds are carbon tetrabromide,bromotrichloromethane, dibromodichloromethane, pentabromoethane, 2,2,2tribromoethane and 1,1,l-tribromo 2 methyl-Z-propanol. Other examples ofsuch compounds and combinations with styryl dyes and dye bases can befound below and in the above-noted patents to Wainer and Sprague andprior applications. In general, a Weight ratio of color former tophoto-initiator of from about 1:5 to about 50:1 is satisfactory.

The color-forming agent is preferably a nitrogen atomcontaining compoundhaving certain structural characteristics. Particularly suitable are (a)compounds having a nitrogen atom that is a member of a heterocyclic ringof up to five atoms, (b) compounds having a benzene nucleus whereby thenitrogen atom is attached to a carbon atom of such benzene nucleus and(c) N-vinyl compounds. It will be appreciated that there may besubstantial overlap between the above types of nitrogen atom-containingcompounds and that our invention is useful with photosensitivecombinations that are formulated with compounds falling within one, twoor all three of the above terms; e.g., N- vinylcarbazole. It will alsobe appreciated that there is no generic term available in acceptedchemical terminology that will effectively embrace all of the abovetypes of compounds. It is merely important to note that photosensitivecombinations containing a compound which has at least one of the abovecharacteristics can be readily improved by our invention. Photosensitivecombinations containing compounds having more than one of the abovecharacteristics lend themselves even better to the process; e.g.,compounds of type (a) in conjugation with a benzene nucleus so that thenitrogen atom is attached to a carbon atom thereof as per compound type(b). Illustrative examples of nitrogen atom-containing compounds includeN-vinylcarbazole, N-ethylcarbazole and indole.

When an N-vinyl compound and organic halogen are dispersed in anon-solubilizing continuous phase, the combination is capable ofundergoing two separate and distinct reactions on exposure to actiniclight. In one reaction, in a negative-working mode, a colored materialis formed in light-struck areas. In another reaction, in apositive-working mode, colorless polymer is thought to be first formedand subsequent blanket exposure to stronger light, forming a color inthe initially non-light-struck areas, yields a positive-working image.These two reactions are competitive, the kinetics of which say that oneor the other will predominate depending on thewavelength-intensityexposure, i.e., the level of light, with thecolorless polymer-forming reaction occurring with weaker light. Additionof an iodide is particularly effective in allowing the occurrence of thepositive mode, non-color, reaction with extended portions of thespectrum.

In the above description of the invention, the term image is used torefer to both color and non-color images. Thus, in one sense, the termincludes images which in their developed form are discernible to the eyeas a result of color formation. However, the term is also being used toinclude images which, even in their developed state, are not necessarilydiscernible to the eye but which are defined by a useful change inphysical or chemical properties, such as photographic sensitivity,solubility, wettability, optical turbidity, hardness, surfacesmoothness, and the like. The term yielding an image is used to refer toimages which develop-out immediately as well as those which are onlypresent in latent form, i.e., they are capable of being later developedeither by the passage of time or by subsequent treatment with light,heat and/ or chemicals.

The following examples will illustrate various aspects of our invention.

EXAMPLE 1 A sheet of baryta paper was coated to about 3 mil wetthickness with an emulsion having the following formulation:

20% gelatin-50 ml.

1.5% Tergitol 410 drops N-vinylcarbazole4.0 g.

Carbon tetrabromide3.2 g. 4-(pdimethylaminostyryl)-quinoline-2 mg.

Ethyl acetate (saturated with Nal, about 0.01 g.)2 ml. Sodium iodide0.1g.

The foregoing emulsion was prepared by adding the Tergitol 4 (a wettingagent) and 1 g. of sodium iodide to the gelatin, adding theN-vinylcarbazole, the 4 (p-dimethylaminostyryl)-quinoline and the carbontetrabromide to the sodium iodide-saturated ethyl acetate and thenmixing the two solutions with high speed stirring for five minutes at 40C.

The foregoing coated sheet and a control sheet (with the same coatingbut omitting the sodium iodide) were exposed for 30 seconds in a Bausch& Lomb spectrograph equipped with a Hanovia watt xenon lamp as a lightsource. The sheets were heated for about ten seconds with a rotatingdrum heater at about 70 C., flooded with a Sylvania Sun Gun 11 (Model86-55) for about one second at about 14 inches and then heated again bypassing through the rotating drum heater. Positive images of theexposure were obtained. The spectral response of the control was foundto extend to about 5600 A. whereas the response of the formulationcontaining sodium iodide was found to extend to 6200 A. (the end of thespectrograph range).

EXAMPLE 2 Emulsions were prepared having the following formulation:

20% gelatin-50 ml.

1.5% Tergitol 410 drops 37% Formalin-2 drops 5% chrome alum5 dropsN-vinylcarbazole--4.0 g. Carbon tetrabromide3.2 g. Acetone-2 ml.

Sodium iodideSee below Sensitizer-See below The emulsions were preparedby adding the Tergitol 4, hardening agents (formalin and chrome alum)and sodium iodide (where present) to the gelatin, adding theN-vinylcarbazole, the sensitizer (where present) and the carbontetrabromide to the acetone and then mixing the two solutions with highspeed stirring for about five minutes at 40 C. Test sheets were thencoated with the emulsion to about 3 mil wet thickness. The test sheetswere exposed for 30 seconds in a Bausch & Lomb spectrograph equippedwith a Hanovia 150 watt xenon lamp and a light source. They weredeveloped by flooding with light for about two seconds from a 275 wattGeneral Electric sun lamp at about 10 inches. This was followed bypassing the test sheets through a rotating drum heater for about 10seconds at about 66 C. The spectral response of each sheet is given inthe following table which also sets forth the amount of sodium iodideand type and amount of sensitizer in each emulsion.

SENSITIZER Sodium Ethyl iodide, g. 4SQ, gJ red, g. Spectral range, A.

1 4-(p-dimethylaminostyryl)-quinoline.

EXAMPLE 3 An emulsion was prepared having the following formulation:

20% gelatin-5O ml.

1.5% Tergitol 410 drops N-vinylcarbazole4.0 g.

Carbon tetrabromide-3.2 g.

4- (p-dimethylaminostyryl) -quinoline2 mg. Ethyl acetate2 ml.

Tetrapropylammonium iodide-1 mg.

The emulsion was prepared by adding the Tergitol 4 and iodide to thegelatin, adding the N-vinylcarbazole, the4(p-dimethylaminostyryl)-quinoline, and the carbon tetrabromide to theethyl acetate and then mixing the two solutions with high speed stirringfor about five minutes at 40 C. Test sheets were then coated with theemulsion to about 1.5 mil wet thickness. The sheets were exposed anddeveloped in a manner similar to that set forth in Example 2. Thespectral response of the sheet was found to be about 2400-6200 A.

EXAMPLE 4 Emulsions were prepared having the following formulation:

20% gelatin50 ml.

1.5% Tergitol 410 drops N-vinylcarbazole4.0 g.

Carbon tetrabromide3.2 g.

4- (p-dimethylaminostyryl -quinoline-2 mg. Ethyl acetate2 ml.

Halogen compound (see below)0.1 g.

The emulsions were prepared by adding the Tergitol 4 and halogencompound to the gelatin, adding the N-vinylcarbazole, the4-(p-dimethylaminostyryl)-quinoline, and

Spectral Halogen compound range, A.

Test sheet:

A Sodium iodate 2,400-5,000 B. Potassium bromide 2, 4005, 000 o Lithiumchloride moo-5,400

It can be seen that no advantage is gained by using an iodate, bromideor chloride in combination with a senSi tizer, in contrast to theresults demonstrated in Examples 1-3.

What is claimed is:

1. In a composition comprising (1) a photosensitive dispersed phase inthe form of discrete globules of a combination of (a) an aryl amine freefrom nuclear substitution in the position para to nuclear attachment ofsaid amine nitrogen atom, and (b) an organic halogen compound selectedfrom the group of compounds which produce free radicals or ions uponexposure to light of a suitable wavelength and in which there is presentat least one active halogen selected from the group consisting ofchlorine, bromine and iodine, attached to a carbon atom having not morethan one hydrogen atom attached thereto, in (2) an aqueous dispersionmedium of a solidhydrophilic-film-forming vehicle in which saiddispersed phase is substantially insoluble, said composition containing(3) a photographic spectral sensitizing dye material, separate anddistinct from the components of said combination, having preferentialattraction for said combination and effecting a photosensitive spectralresponse to said combination differing from the spectral response ofeach of the components thereof per se and said combination in theabsence of said dye material, said dye material being in a form selectedfrom the dye form and the dye base form, the combination therewith of aniodide.

2. The invention according to claim 1 in which said iodide is selectedfrom alkali metal and ammonium iodides.

3. The invention according to claim 1 in which said iodide is sodiumiodide.

4. The invention according to claim 1 in which said iodide is potassiumiodide.

5. In a composition comprising (1) a photosensitive dispersed phase inthe form of discrete globules of a combination of (a) an N-vinylcompound and (b) an organic halogen compound selected from the group ofcompounds which produce free radicals or ions upon exposure to light ofa suitable wavelength and in which there is present at least one activehalogen selected from the consisting of chlorine, bromine and iodine,attached to a carbon atom having not more than one hydrogen atomattached thereto in (2) an aqueous dispersion medium of asolid-hydrophilic-film-forming vehicle in which said dispersed phase issubstantially insoluble, said composition containing (3) a photographicspectral sensitizing dye material, separate and distinct from thecomponents or said combination, having preferential attraction for saidcombination and effecting a photosensitive spectral response to saidcombination differing from the spectral response of each of thecomponents thereof per se and said combination in the absence of saiddye material, said dye material being in a form selected from the dyeform and the dye base form, the combination therewith of an iodide.

6. The invention according to claim 5 in which said dye material isselected from the rhodamines, the pinacyanoles, the eosins, thetriphenylmethanes, the thiazines, the anthraquinoids and the styryl dyesand dye bases.

7. The invention according to claim 5 in which said dispersion medium isselected from the group consisting of gelatin, casein, polyvinylalcohol, gum arabic, starch, sodium carboxymethylcellulose andhydroxyethylecellulose.

8. The invention according to claim 5 in which said N- vinyl compound iscapable of undergoing two separate and distinct reactions on exposure toactinic light and in the presence of said organic halogen compound.

9. The invention according to claim 5 in which said iodide is selectedfrom alkali metal and ammonium idides.

10. The invention according to claim in which said iodide is sodiumiodide.

11. The invention according to claim 5 in which said iodide is potassiumiodide.

12. In a composition comprising (1) a photosensitive dispersed phase inthe form of discrete globules of a combination of (a) a nitrogenatom-containing compound selected from the group consisting of N-vinylcarbazole, N-ethyl carbazole, indole and diphenylamine, and (b) anorganic halogen compound selected from the group of compounds whichproduce free radicals or ions upon exposure to light of a suitablewavelength and in which there is present at least one active halogenselected from the group consisting of chlorine, bromine and iodine,attached to a carbon atom having not more than one hydrogen atomattached thereto in an (2) aqueous dispersion medium of asolid-hydrophilic-film-forming vehicle in which said dispersed phase issubstantially insoluble, said combination being responsive to actiniclight to yield an image of selective light absorptivity distinct fromthat of said combination and said nitrogen atom-containing compound andorganic halogen compound, said composition containing (3) a photographicspectral sensitizing dye material, separate and distinct from thecomponents of said combination, having preferential attraction for saidcombination and effecting a photosensitive spectral response to saidcombination diifering from the spectral response of each of thecomponents thereof per se and said combination in the absence of saiddye material, said dye material being in a form selected from the dyeform and the dye base form, the combination therewith of an iodide.

13. In a composition consisting essentially of (1) a photosensitivedispersed phase in the form of substantially fine spheroidal solidparticles of N-vinylcarbazole and carbon tetrabromide fused into a mildyellow substantially homogenous combination in (2) an aqueous,substantially translucent continuous solid-hydrophilic-filmforming-phasein which the dispersed phase is substantially insoluble, saidcombination being selectively photoreactive to produce a coloring agentand to produce a photoinsensitive agent of substantially the samevisible appearance as said photosensitive combination, said compositioncontaining (3) a photographic spectral sensitizing dye material,separate and distinct from the components of said combination, havingpreferential attraction for said combination and effecting aphotosensitive spectral response to said combination, differing from thespectral response of each of said components per se and said combinationin the absence of said dye material, said dye material being in a formselected from the dye form and dye base form, the combination therewithof an iodide.

14. In a composition consisting essentially of (1) a photosensitivedispersed phase in the form of substantially fine spheroidal solidparticles of N-vinylcarbazole and hexachloroethane fused into asubstantially colorless homogeneous combination in (2) an aqueous,substantially translucent continuous solid-hydrophilic-film-formingphase in which the dispersed phase is substantially insoluble, saidcombination being selectively photo-reactive to produce a coloring agentand to produce a photo-insensitive agent of substantially the samevisible appearance as said photosensitive combination, said compositioncontaining (3) a photographic spectral sensitizing dye material,separate and distinct from the components of said combination, havingpreferential attraction for said combination and efiecting aphotosensitive spectral response to said combination differing from thespectral response of each of the components thereof per se and saidcombination in the absence of said dye material, said dye material beingin the form selected from the dye form and the dye base form, thecombination therewith of an iodide.

15. In a combination which is photosensitive in a hydrophilic binder,comprising (1) an organic halogen compound having the formula wherein X,X and X are halogens, each Y is independently selected from the groupconsisting of halogen, hydrogen, hydroxy, methyl and methylol, and n isselected from O and 1, such that when n is O, X and X are Br, (2) anaromatic amine, and (3) a styryl dye material in a form selected fromthe dye form and dye base form, the combination therewith of an iodide.

16. The invention according to claim 15 in which said iodide is selectedfrom alkali metal and ammonium iodides.

17. The invention according to claim 15 in which said iodide is sodiumiodide.

18. The invention according to claim 15 in which said iodide ispotassium iodide.

19. The invention according to claim 15 in which said styryl dye or dyebase is 4-(p-dimethylaminostyryl)-quinoline dye or dye base.

20. The invention according to claim 15 in which said styryl dyematerial is in the dye base form.

21. The invention according to claim 20 in which said aromatic amine isan N-vinyl compound.

22. The invention according to claim 21 in which said N-vinyl compoundis N-vinylcarbazole and said organic halogen is carbon tetrabromide.

23. The invention according to claim 22 in which said styryl dye or dyebase is 4-(p-dimethylaminostyryl)- quinoline dye or dye base.

References Cited UNITED STATES PATENTS 2,099,297 11/1937 Clement 96-483,042,518 7/1962 Wainer 96--90X NORMAN G. TORCHIN, Primary Examiner R.E. FIGHTER, Assistant Examiner US. Cl. X.R. 9688

